Layer 0 is base layer without modifiers. Layer 1 could be accessed by Caps Lock. Layer 2 could be accessed by AltGr. Uppercase requires Shift in down position; can also try macro to capitalize the previous word.

If other hand is able, even staying at home keys to press modifiers would provides access to at least six layers. Base layer is unmodfied, then each offhand finger at home is another layer individually; if simultaneous modifiers is achievable, that's exponentially more layers.